Porphobilinogen is a dicarboxylic acid that is pyrole bearing aminomethyl, carboxymethyl and 2-carboxyethyl substituents at positions 2, 3 and 4 respectively. It has a role as a metabolite, an Escherichia coli metabolite and a mouse metabolite. It is a member of pyrroles, a dicarboxylic acid and an aralkylamino compound. It is a conjugate acid of a porphobilinogen(1-).